An apparatus includes a first and second driving circuits that energize a first and third heat generating blocks; a first and second temperature detection members that detect each temperature of the first and third heat generating blocks; a control portion that controls the first and second driving circuits according to at least one of the temperatures detected by the first and second temperature detection members; and a connection switching portion that selectively connects any one of the first and second driving circuits to a second heat generating block according to a switching instruction from the control portion. The control portion controls energization of the second heat generating block together with a heat generating block which is energized by the driving circuit connected to the second heat generating block.

An image formation apparatus includes: one or more image formation units; one or more heaters; a first voltage converter which generates a direct first voltage based on an alternating external input voltage inputted from outside of the first voltage converter; a second voltage converter which generates an alternating second voltage based on the first voltage, the second voltage supplying alternating-current power to the one more heaters; a third voltage converter which generates a third voltage based on the first voltage, the third voltage being used to drive at least the one or more heaters; a controller which performs an operation control of reducing power consumption in at least the one or more heaters when the external input voltage decreases to a range of a first threshold or lower and higher than a second threshold and/or when a load change of the first voltage converter is lower than a third threshold.

The present subject matter describes a heating unit. The heating unit comprises a heating element and a controlling unit coupled to the heating element to determine a desired value of a direct current (DC) voltage based on heating element parameters. The desired value is a value of DC voltage desired for operation of the heating element. The controlling unit computes a value of a duty cycle parameter based on device input parameters and the desired value of the DC voltage. The heating unit further comprises a power factor correction (PFC) unit coupled to the controlling unit and the heating element to convert an input alternating current (AC) voltage, received by the PFC unit from an AC supply, to a direct current (DC) voltage of the desired value based on the duty cycle parameter. The PFC unit provides the DC voltage to the heating element.

A sheet thermocompression apparatus for bonding a plurality of the sheets to one another, and configured to be compatible with the sheets with a plurality of prescribed sizes. The apparatus includes a loading portion to be loaded with the bundle of sheets each including the adhesion layer formed thereon and a thermocompression unit. The thermocompression unit includes (i) a pressing member pressing the bundle of sheets loaded on the loading portion in a loading direction of the sheets, a longitudinal direction of the pressing member is a direction along one edge of the sheets loaded on the loading portion, (ii) a heating source heating the pressing member, and (iii) a temperature measuring sensor arranged at a position not overlapping a minimum sheet with a minimum size of the prescribed sizes loaded on the loading portion in the loading direction, and detects a temperature of the heating source.

A sheet conveyor includes a heating device to heat a recording medium and a recording medium sensor to detect the recording medium. The heating device includes a heater, a first temperature sensor to detect a temperature of the heater, and a second temperature sensor to detect the temperature of the heater. The heater has a first heat-distribution amount region on one side and a second heat-distribution amount region on the other side, in a conveyance orthogonal direction with respect to a reference position. The first heat-distribution amount region is greater in heat distribution amount than the second heat-distribution amount region. The first temperature sensor is disposed farther from the reference position than the second temperature sensor in the conveyance orthogonal direction. The first temperature sensor is disposed in the second heat-distribution amount region. The recording medium sensor is disposed in the first heat-distribution amount region.

An image formation apparatus includes: one or more image formation units; one or more heaters; a first voltage converter which generates a direct first voltage based on an alternating external input voltage inputted from outside of the first voltage converter; a second voltage converter which generates an alternating second voltage based on the first voltage, the second voltage supplying alternating-current power to the one more heaters; a third voltage converter which generates a third voltage based on the first voltage, the third voltage being used to drive at least the one or more heaters; a controller which performs an operation control of reducing power consumption in at least the one or more heaters when the external input voltage decreases to a range of a first threshold or lower and higher than a second threshold and/or when a load change of the first voltage converter is lower than a third threshold.

A heater including a substrate, a first heat generating line provided on the substrate and in a longitudinal direction of the substrate, the first heat generating line being divided into a plurality of heat generating blocks in the longitudinal direction, the plurality of heat generating blocks being controllable independently, and a second heat generating line provided on the substrate and in the longitudinal direction of the substrate, the second heat generating line being divided into a plurality of heat generating blocks in the longitudinal direction, the plurality of heat generating blocks being controllable independently. In the heater, divided positions of the first heat generating line and divided positions of the second heat generating line are different.

A heater control device includes a power factor correction circuit configured to convert an alternate current voltage from a commercial power source to a direct current voltage; an inverter configured to generate a specific alternate current voltage from the direct current voltage converted with the power factor correction circuit; a heater configured to receive the specific alternate current voltage generated with the inverter; and an excessive temperature rise preventing portion configured to interrupt the specific alternate current voltage generated with the inverter from being supplied to the heater.

A heating device includes a plurality of chip resistors, a conductor pattern, and a substrate. The plurality of chip resistors generate heat upon receiving power from a power source. The conductor pattern is arranged so as to serially connect the plurality of chip resistors. The conductor pattern is formed on the substrate. The conductor pattern connecting the chip resistors is wider in a forward path from the power source than in a backward path. The majority of the heat generated by the chip resistor is transmitted from the chip resistor to the conductor pattern, and the transmitted heat is radiated from the conductor pattern. Thus, not only the heat from the surface of the chip resistor but also the heat from the conductor pattern serves as heat source.

A heater including a substrate, a first heat generating line provided on the substrate and in a longitudinal direction of the substrate, the first heat generating line being divided into a plurality of heat generating blocks in the longitudinal direction, the plurality of heat generating blocks being controllable independently, and a second heat generating line provided on the substrate and in the longitudinal direction of the substrate, the second heat generating line being divided into a plurality of heat generating blocks in the longitudinal direction, the plurality of heat generating blocks being controllable independently. In the heater, divided positions of the first heat generating line and divided positions of the second heat generating line are different.